[unreadable] This supplemental research proposal for clinical resident research experience seeks to validate tomography algorithms, instrumentation, and imaging agents developed under the parent grant, "Small animal fluorescence enhanced optical imaging." Using a dual-labeled, optical and nuclear imaging agent targeted to the alpha-v-beta-3 integrin, we propose to compare a "gold-standard" of preclinical tomography, micro- SPECT with time-dependent fluorescence tomography. Owing to the short duration of the proposed research project, we will deploy existing technology developments to assess the molecular specificity of an optical/nuclear integrin-targeting imaging agent and assess its biodistribution within an orthotopic animal model of integrin expressing metastatic melanoma. Specifically we will: 1. Assess the molecular specificity of imaging agents c(KRGDf)-IRDye800, 1111n-c(KRGDf), and 1111n- c(KRDGf)-IRDye800 through competitive binding and determination of IC50 in cell cultures of integrin positive M21 and integrin negative M21-L; 2. Perform SPECT and fluorescence-enhanced optical imaging of c(KRGDf)-IRDye800, 1111n-c(KRGDf), and 111 ln-c(KRDGf)-IRDye800 and compare imaging figures of merit as SUV, TBR, and SNR; 3. Assess the biodistribution of agents via comparison of tomographic images with co-registered micro-CT; and 4. Use autoradiography, fluorescence microscopy, and immunohistochemistry to assess the tissue location of targeting agents. This project will not focus upon technology development, but instead will use established and newly developed technologies. If successful, this project will provide the first validation of optical tomography in a preclinical model of metastatic cancer. [unreadable] [unreadable] [unreadable]